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Oral Oncol. 2008 Jun;44(6):587-94. Epub 2007 Oct 23.

Iron increases MMP-9 expression through activation of AP-1 via ERK/Akt pathway in human head and neck squamous carcinoma cells.

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Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant Road, Pathumwan, Bangkok, Thailand.


Head and neck squamous cell carcinoma (HNSCC) is a highly invasive cancer that is capable of distant metastasis and is a cause of great morbidity and mortality worldwide. Over-expression of matrix metalloproteinase-9 (MMP-9) is implicated in the invasion and metastasis of HNSCC. There is increasing evidence of an association between iron overload and cancer progression. However, the effect of iron on MMP-9 expression in HNSCC has not been studied. In the present study, we examined the effect of iron on MMP-9 expression in head and neck squamous carcinoma cell lines (OM-2 and HN-22). Ferric ammonium citrate (FAC), a source of iron, at 15 microg/ml increased MMP-9 in both cell lines in a dose-dependent manner as shown by reverse transcription polymerase chain reaction and gelatin zymography analyses. Studies using specific inhibitors of extracellular signal-regulated kinase (ERK1/2) and of Akt (SH-5) demonstrated that iron regulated MMP-9 through ERK1/2 and Akt, and that ERK1/2 was an upstream activator of Akt. Analysis of electrophoretic mobility shift assay revealed that iron induces MMP-9 expression by activation of activated protein-1 (AP-1). Application of neutralizing antibody against transferrin receptor could not abolish the stimulated MMP-9 expression, suggesting that iron uptake is non-transferrin dependent. In conclusion, this study is the first to demonstrate that MMP-9 was up-regulated by iron in HNSCC cell lines. We suggest that iron may be one of several factors that cause an increase of MMP-9, which is necessary for the development and progression of HNSCC.

[Indexed for MEDLINE]

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